* {
  /* 初始化显示 */
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body,
canvas {
  /* 让窗口保持一个屏幕内 */
  width: 100vw;
  height: 100vh;
  background-color: #000000;
  overflow: hidden;
}
